"""Runtime camera add/remove on a live Engine — stubbed so no models load."""
import threading
import time

import pytest

from behavision.cameras import CameraStore
from behavision.config import CameraConfig, Config
from behavision.engine import Engine


class FakeWorker:
    def __init__(self, cam_cfg, *a, **kw):
        self.cam_cfg = cam_cfg
        self.started = self.stopped = self.joined = False
        self._alive = False

    # Faithful to threading.Thread: stop() only signals - the thread stays
    # alive until its loop exits, and join() on a never-started Thread raises.
    def start(self): self.started = self._alive = True
    def stop(self): self.stopped = True
    def is_alive(self): return self._alive
    def join(self, timeout=None):
        if not self.started:
            raise RuntimeError("cannot join thread before it is started")
        self.joined = True
        self._alive = False
    def stats(self): return {"camera_id": self.cam_cfg.id}


@pytest.fixture
def engine(tmp_path, monkeypatch):
    """Engine without __init__ — no ONNX, no camera, no gallery."""
    monkeypatch.setattr("behavision.engine.CameraWorker", FakeWorker)
    monkeypatch.setattr("behavision.engine.FaceDetector",
                        lambda *a, **kw: object())
    eng = object.__new__(Engine)
    eng.cfg = Config()
    eng.cfg.app.data_dir = tmp_path
    eng.encoder = eng.gallery = eng.bus = eng.attributes = None
    eng._lock = threading.RLock()
    eng.workers, eng.detectors = {}, {}
    eng.started_at, eng._running = None, True
    eng.camera_store = CameraStore(tmp_path / "cameras.json")
    return eng


def cam(cid): return CameraConfig(id=cid, host="10.0.0.1")


def test_add_camera_starts_it_on_a_running_engine(engine):
    w = engine.add_camera(cam("a"))
    assert w.started and engine.workers["a"] is w
    assert "a" in engine.detectors


def test_each_camera_gets_its_own_detector(engine):
    """Sharing one cv2.FaceDetectorYN across workers races on input size."""
    engine.add_camera(cam("a"))
    engine.add_camera(cam("b"))
    assert engine.detectors["a"] is not engine.detectors["b"]


def test_duplicate_camera_id_rejected(engine):
    engine.add_camera(cam("a"))
    with pytest.raises(ValueError, match="already running"):
        engine.add_camera(cam("a"))


def test_remove_camera_stops_and_joins(engine):
    w = engine.add_camera(cam("a"))
    assert engine.remove_camera("a")
    assert w.stopped and w.joined
    assert "a" not in engine.workers and "a" not in engine.detectors
    assert not engine.remove_camera("a")


def test_restart_builds_a_new_worker(engine):
    """CameraWorker is a Thread; a stopped Thread cannot be restarted, so an
    edited URL must produce a fresh object."""
    first = engine.add_camera(cam("a"))
    second = engine.restart_camera(CameraConfig(id="a", host="10.0.0.99"))
    assert second is not first
    assert first.stopped and second.started
    assert engine.workers["a"].cam_cfg.host == "10.0.0.99"


def test_camera_added_before_start_is_not_started_yet(engine):
    engine._running = False
    w = engine.add_camera(cam("a"))
    assert not w.started


def test_removing_a_never_started_camera_does_not_raise(engine):
    """join() on an unstarted Thread raises RuntimeError - the is_alive()
    guard in remove_camera is what prevents it."""
    engine._running = False
    w = engine.add_camera(cam("a"))
    assert engine.remove_camera("a")
    assert w.stopped and not w.joined


def test_stats_tolerates_a_concurrent_remove(engine):
    """snapshot_workers() exists so stats() cannot trip over a dict being
    mutated by an API thread mid-iteration."""
    for i in range(40):
        engine.add_camera(cam(f"c{i}"))
    errors = []

    def churn():
        try:
            for i in range(40):
                engine.remove_camera(f"c{i}")
                time.sleep(0.001)
        except Exception as exc:  # noqa: BLE001
            errors.append(exc)

    def read():
        try:
            for _ in range(200):
                [w.stats() for w in engine.snapshot_workers()]
        except Exception as exc:  # noqa: BLE001
            errors.append(exc)

    ts = [threading.Thread(target=churn), threading.Thread(target=read)]
    for t in ts: t.start()
    for t in ts: t.join()
    assert not errors, errors


# ---------------------------------------------------------------- real threads

# Every test above stubs the worker, which is why a real threading bug lived
# here undetected: `join()` on a started CameraWorker raised
# "'Event' object is not callable", so removing or editing a camera at runtime
# answered 500 - the exact path head office uses to push a camera to a shop PC.
# These two use the real classes and the real Thread machinery.
def test_a_started_capture_thread_can_be_stopped_and_joined():
    from behavision.capture import VideoSource

    src = VideoSource("cam1", "rtsp://127.0.0.1:1/none", "rtsp://127.0.0.1:1/none", 1280)
    src.start()
    time.sleep(0.05)
    src.stop()
    src.join(timeout=5)
    assert not src.is_alive()


def test_a_started_camera_worker_can_be_stopped_and_joined(tmp_path):
    from behavision.engine import CameraWorker

    cfg = Config()
    cfg.app.data_dir = tmp_path
    cam = CameraConfig(id="cam1", host="127.0.0.1", port=1, path="/none")
    # The collaborators are never reached: the source cannot connect, so the
    # loop only ever sees `frame is None`.
    w = CameraWorker(cam, cfg, detector=None, encoder=None, gallery=None,
                     bus=None, attrs=None)
    w.start()
    time.sleep(0.05)
    w.stop()
    w.join(timeout=5)
    assert not w.is_alive()